The present invention relates to production of exposure data for an exposure apparatus from circuit design pattern data for a semiconductor integrated circuit and the like, and more particularly to a technique for compressing design pattern data, and for example, to exposure data production for a semiconductor device and the like including many repetitive pattern segments such as a semiconductor memory device.
As semiconductor integrated circuits become large in scale and microscopic in circuit patterns, a technique for drawing patterns on a mask or a wafer by utilizing an electron beam exposure apparatus has been adopted. In order to draw a predetermined pattern on a mask or a wafer with an electron beam exposure apparatus by using design pattern data for LSI devices prepared through logic design, circuit design and layout design, such pattern data will have to be converted to exposure data for an electron beam exposure apparatus. Such conversion is performed for the purpose of: overlap removal so that exposure accuracy is not lowered by multiple exposure due to overlap between pattern elements in a pattern defined by design pattern data; size correction in case it is desired to enlarge or reduce pattern elements defined by pattern data; proximity effect correction against scattering of an electron beam in pattern drawing; processing of decomposing patterns into fundamental pattern elements which are able to be drawn with an electron beam exposure apparatus; and so forth. The data conversion described above is usually performed with a large computer.
Recently, the amount of data to be processed by an electron beam exposure apparatus goes on increasing as an LSI device becomes large in scale and microscopic in circuit pattern. In the conventional electron beam exposure technique, conversion of a design pattern data to an exposure data has been made one by one on all the pattern elements defined by the design pattern data to be converted. Therefore, computer processing time required for the data conversion and exposure data amount are increased, and efficient conversion to exposure data has not been possible with a highly integrated LSI device such as a DRAM.
Thus, a technique which performs compression of exposure data has been proposed for the purpose of reducing the exposure data amount. JP-A-57-122529 (laid-open on Jul. 30, 1982) may be mentioned as an example in which such a technique is described. According to this publication, repetitive patterns defined by an exposure data for the whole of a pattern having been converted from a design pattern data are recognized, and pattern segments representing all regions including identical repetitive pattern segment are entered and utilized repeatedly for corresponding regions, thereby to compress the amount of data necessary in practical pattern drawing.